checkrestart is a program designed to help to find processes that need
restarting after upgrade.

checkrestart walks thought entire file table of the system, searching for
processes using node detached from filesystem.

The typical use case is:
 - starts a long lived program.
 - later, upgrades your packages via pkg_add -u.
 - if the program is updated on disk, the running program is still the
   previous one (without security fixes for example).
 - checkrestart will tell you which processes belong to this category.
